There are numerous different methods for exercising muscles of the human body. Many involve no requirement for equipment at all, simply involving a person following a defined movement that concentrates loads on particular muscle groups. Many methods, however, do involve equipment, and for a range of reasons—to enable larger forces to be obtained, to better target particular muscle groups than ordinary exercise regimes can do, and to allow more easy regulation of progress from easy exercise to more demanding. One popular exercise method involves the use of “free” weights, such as barbells and so-called “dumb-bells”. The use of free weights is desirable for such reasons as these.
In addition to the advantages which free weights offer, there are also several disadvantages. First, it is difficult to isolate some muscle groups with free weights because of the awkward angle at which the free weight must be moved during the exercise. Additionally, many lifts involving free weights require the use of a “spotter”, i.e. an assistant. If the lifter is unable to complete the lift, the spotter must step in and quickly assist in the lift to prevent physical harm from being incurred by the lifter. Nowhere is this more important than in bench presses, in which a barbell is lifted above the body of a lifter lying on his (or her) back. If the lifter is unable to lift the weights and no spotter is available, the barbell can land on the lifter's throat, causing serious injury or even death.
Because many individuals wish to work out at home or wish to avoid the use of a spotter, there has been a marked increase in the popularity of mechanical devices in which one or more movable parts are moved by the user against resistance generated by, for example, weights, springs, or even the user's own weight. Multi-function equipment in particular has proven popular, due to its ability to provide a range of exercises, targeted to develop particular muscle groups. As with free weights, such machines when used continuously or repetitively involve the expenditure of effort and so also aid the improvement of fitness (eg heart and lung function).
Such equipment most usually includes at least one weight stack which engages a cable which is in turn pulled by the user. Typically this is accomplished by an elongate metal shaft with a plurality of holes which extends through the stack of weights. A locking pin is inserted into one of the holes and all weights above the locking pin are lifted with each pull on the cable. The cable may be pulled directly by a user, or alternatively the user may move a mechanical component which is itself linked to the cable directly or indirectly via various types of mechanisms.
One disadvantage of such equipment, however, is that the resistance felt by a user often varies throughout the normal range of movement, often in a way that is not ideal for the user. For example, some equipment tends to focus the exertion of each lift at the beginning of each muscle movement. In other words, once the cable has begun to move the associated weights, the effort involved with moving the weights through the remainder of the repetition decreases significantly. This can affect muscle use and development. For this reason, many serious body builders will not use multi-function machines. This problem also limits the ability of the user to focus on a particular area of weakness along the muscle's movement. For example, a user may determine that he is not as strong as desired in the last 60 degrees of a biceps curl when using free weights or may desire to tone his biceps to provide a more rounded curve. With the present multi-function machines and even single station cable-based exercise machines, strengthening or toning as desired can be extremely difficult.
The available multi-function exercise machines also have a number of other problems. For example, some machines will only allow a user to perform a few different exercises, e.g. they may only work the arms or legs, often in only a limited number of ways. Others are overly complex and costly. Thus there is a need for an improved multi-function exercise apparatus that addresses these problems.
The problem of providing resistance to movement of a member of an exercise apparatus, with that resistance varying along the path of the member in a desired way, has been recognized, and addressed in various ways. One class of machine is based on a weight being supported on a member rotatably mounted on a shaft journalled in a frame, the shaft being rotated by a lever or other mechanism through the effort of a user. A starting position (i.e. lateral displacement from the shaft axis) of the weight can be varied so that the starting torque applied to the shaft to resist the user-generated torque, and the nature of its variation as the shaft is rotated, can be adjusted to a degree. One example of this approach is disclosed by Hobson (U.S. Pat. No. 6,350,219). A problem with such devices is that only a limited degree of control of resistance variation is possible.
An alternative approach, and the one thought to be the most commonly used, is thought to be that exemplified by such devices as those of Kasigkeit (Australian patent application 57830/86), Johns (U.S. Pat. No. 5,356,360), and Solow (U.S. Pat. No. 5,102,121), in which a cable or chain extends from a weight stack over a rotatable cam which in turn is rotated (directly or via one or more intermediate members) by a user. See also U.S. Pat. Nos. 4,511,137, 4,666,152, 4,807,874, 4,957,281 and European Patent 0391315, all of which are examples of such cam-based exercise machines. The torque applied by the weight to resist its rotation depends on the shape of the cam. This approach is in reality a variation on the previous one, in that the resisting torque applied to a rotating member depends on the distance from that member's axis at which a constant force is applied. There are limitations to the nature of the resistance variation that can be provided in this way. For example, variation in resistance over a very short distance is difficult to provide. There are also limitations to the ease with which the nature of the resistance variation can be changed at will for a given exercise or to suit a different exercise.
The exercise apparatus disclosed herein addresses the problems of multi-function machines set out above, while allowing a large number of different exercises to be carried out. Moreover, the machine lends itself to being modified to provide modulated resistance for improved workout for various muscle groups. “Modulated” here means that the resistance to movement felt by a user of apparatus during each repetition of a particular exercise (or part of an exercise) varies with movement along the stroke.
Other types of exercise apparatus provide a degree of variation of resistance simply through progressive change of relative orientation of their parts during use. An example is the apparatus of Stearns (U.S. Pat. No. 5,658,227), which uses an arrangement of pin-jointed links to provide movement, but with variation of resistance not being a particular objective. U.S. Pat. No. 6,074,328 also discloses a machine of this class. The modulation of resistance discussed herein is to be understood as variation that is additional to and distinct from such variation, but need not necessarily be of smaller magnitude.
A mechanical arrangement is disclosed herein which can provide modulation of the resistance felt by a user of exercise apparatus in the above sense. The arrangement also enables the nature of that variable (modulated) resistance to itself be changed conveniently.
The multifunction exercise apparatus disclosed herein lends itself to use of the said arrangement, and is preferably provided with it. However, the exercise apparatus is also considered to offer a useful alternative to others in the market when the variable resistance arrangement is disabled or even excluded altogether.
Moreover, the variable resistance arrangement disclosed is also applicable in types of exercise apparatus other than the preferred one here disclosed.